Thermo-Mechanical and ILSS Properties of Woven Carbon/Epoxy-XD-CNT Nanophased Composites

Abstract

Carbon fiber-reinforced epoxy composites (CFEC) were fabricated infusing 0, 0.15, 0.30, and 0.40 wt% amino-functionalized XD-grade carbon nanotubes (NH₂-XDCNTs) using the compression molding process under 16 kips. The thermo-mechanical and interlaminar shear properties of CNT incorporated carbon/epoxy composite samples were evaluated by performing dynamic-mechanical thermal analysis (DMTA) and short beam shear (SBS) tests. XD-CNTs were infused into Epon 862 resin using a mechanical stirrer followed by a high intensity ultrasonic liquid processor for better dispersion. After the sonication, the mixture was placed in a three roll milling processor for 3 successive cycles at 140 rpm, with the gap spaces incrementally reduced from 20 to 5 μm, to obtain the uniform dispersion of CNTs throughout the resin. Epikure W curing agent was then added to the modified resin and mixed using a high-speed mechanical stirrer. Finally, the fiber was reinforced with that modified resin using the compression molding process. The results obtained from the DMTA test were analyzed based on the storage modulus, glass transition temperature, and loss modulus. The analysis indicated that the thermo-mechanical properties were linearly increasing from 0 to 0.3 wt% XDCNT loading. The SBS test results exhibited that the incorporation of XDCNTs into the composite increased the interlaminar shear strength (ILSS) by up to 22% at 0.3 wt% CNT loading. Better dispersion of XDCNTs might be attributed to more crosslinking sites and better interaction between fiber and matrix resulting in an improved fiber-matrix interface, whereas, the reaction between functional groups–NH₂ of XDCNTs with epoxide groups of resin and epoxy silanes of fiber surfaces improved the crosslinking and thereby ILSS properties of carbon/epoxy composites.